78 Matching Results

Search Results

Advanced search parameters have been applied.

Apiary B Factory Lattice Design

Description: The Apiary B Factory is a proposed high-intensity electron-positron collider. This paper presents the lattice design for this facility, which envisions two rings with unequal energies in the PEP tunnel. The design has many interesting optical and geometrical features due to the needs to conform to the existing tunnel, and to achieve the necessary emittances, damping times and vacuum. Existing hardware is used to a maximum extent.
Date: May 3, 1991
Creator: Donald, M.H.R. & Garren, A.A.
Partner: UNT Libraries Government Documents Department

Next generation of electron-positron colliding beam machines

Description: The contribution of electron-positron colliding beam experiments to high-energy physics in the 1970's has been prodigious. From the research done with the two highest-energy e/sup +/e/sup -/ machines of the present generation of these devices, have come such things as the discovery and illumination of the properties of the psi family, charmed particles, a new heavy lepton, non-ambigious evidence for hadronic jets, etc. The rapid pace of new developments in physics from such machines comes about for two reasons. First, the electron-positron annihilation process at present energies is particularly simple and well understood, making the problem of determining the quantum numbers and properties of new particles particularly simple. Second, in electron-positron annihilation all final states are on a relatively equal footing, and small production cross sections are compensated for by a lack of confusing background. For example, the rate of production of charmed particles at the SPEAR storage ring at SLAC and the DORIS storage ring at DESY is 3 or 4 orders of magnitude less than the rate of production at FNAL and the SPS. Yet these particles were first found at the storage rings where the background cross sections are comparable to the signal cross section, and have not yet been observed directly by their hadronic decays at the proton machines where the background cross sections are 4 orders of magnitude larger than the signal cross sections. The machines PEP at SLAC and PETRA at DESY will soon be operating at 35 to 40 GeV cm to explore new regions of energy. Studies of electron-positron annihilation at much higher energies than presently planned have a great deal to teach, not only about particle structure and dynamics, but also about the nature of the weak interaction. Some of the physics which can be done with such machines is discussed ...
Date: March 1, 1979
Creator: Richter, B.
Partner: UNT Libraries Government Documents Department

An investigation of positrons interacting with solid argon, krypton and xenon

Description: With this article we intend to shed some light on all the important characteristics of the up-to-date most efficient positron moderators, the rare gas solids. We stress on the importance of the impurities in the performance of the solid rare gas moderators. The impurity factor is linked with the crystalline changes to explain the effect of annealing, and demonstrate the role of impurities in the endurance. Significant increase in the low energy positron yield is observed after repeated anneals. The positron energy distributions from Ar, Kr, and Xe moderators are measured to be about 2 eV (FWHM).
Date: October 1, 1996
Creator: Petkov, M.P.; Roellig, L.O. & Troev, T.D.
Partner: UNT Libraries Government Documents Department

HIGH ENERGY MUON COLLIDERS.

Description: A plausible ''straw-man'' scenario and collider ring parameter sets are presented for future energy frontier muon colliders in symbiotic facilities with e{sup +}e{sup -} and hadron colliders: 1.6-10 TeV ''mu-linear colliders'' (mu-LC) where the muons are accelerated in the linacs of a TeV-scale linear e{sup +}e{sup -} collider, and a 100 TeV Very Large Muon Collider (VLMC) that shares a facility with a 200 TeV Very Large Hadron collider (VLHC) and a 140 TeV muon-proton collider.
Date: June 18, 2001
Creator: KING, B.J.
Partner: UNT Libraries Government Documents Department

Determining tan {beta} at the NLC with SUSY Higgs bosons

Description: The authors examine the prospects for determining tan {beta} from heavy Higgs scalar production in the minimal supersymmetric standard model at a future e{sup +}e{sup {minus}} collider. Their analysis is independent of assumptions of parameter unification, and they consider general radiative corrections in the Higgs sector. Bounds are presented for {radical}s = 500 GeV and 1 TeV, several Higgs masses, and a variety of integrated luminosities. For all cases considered, it is possible to distinguish low, moderate, and high tan {beta}. In addition, the authors find stringent constraints for 3 {approx_lt} tan{beta} {approx_lt} 10, and, for some scenarios, also interesting bounds on high tan {beta} through tbH{sup {+-}} production. Such measurements may provide strong tests of the Yukawa unifications in grand unified theories and make possible highly precise determinations of soft SUSY breaking mass parameters.
Date: July 1, 1997
Creator: Feng, J.L. & Moroi, Takeo
Partner: UNT Libraries Government Documents Department

Multi-hadron final states.

Description: This summary aims to highlight major results and insights gained from recent studies of hadronic final states in ep, p{bar p}, e{sup +}e{sup -}, as well as relevant theoretical developments, presented in the Multi-hadron final states parallel sessions of the DIS2002 workshop held in Krakow, Poland in May 2002.
Date: August 29, 2002
Creator: Repond, J.
Partner: UNT Libraries Government Documents Department

Positron annihilation in perfect and imperfect metals: a brief review

Description: The current renaissance of investigations of positron annihilation in solids has its origins in the observation that positrons interact strongly with certain crystal-lattice defects. Three properties of the annihilation process are being measured to gain information about the defects or about the local environment of the positron at the instant of its annihilation: positron lifetime, angular correlation of the two annihilation quanta, and Doppler broadening of the 511-keV annihilation line. Until the physics of positron behavior in solids is fully understood, the phenomenon will continue to be useful in a manner analogous to electrical resistivity recovery for identifying the recovery stages in irradiated metals. Ultimately, it is destined to provide detailed quantitative information such as the formation volume of vacancies, vacancy-impurity binding energies and electron momentum distributions and densities at defect sites. 2 tables, 52 refs. (auth)
Date: January 1, 1975
Creator: Goland, A.N.
Partner: UNT Libraries Government Documents Department

Production of pseudoscalar Higgs-bosons in e {gamma} collisions

Description: We investigate the production of a pseudoscalar Higgs-boson A{sup 0} using the reaction e{gamma} {yields} e A{sup 0} at an e{bar e} collider with center of mass energy of 500 GeV. Supersymmetric contributions are included and provide a substantial enhancement to the cross section for most values of the symmetry breaking parameters. We find that, despite the penalty incurred in converting one of the beams into a source of backscattered photons, the e{gamma} process is a promising channel for the detection of the A{sup 0}.
Date: August 21, 1995
Creator: Dicus, D.A. & Repko, W.W.
Partner: UNT Libraries Government Documents Department

Storage Rings for Science with: Electron-Positron Collisions, Hadron Collisions and Synchrotron Light

Description: The author is honored to receive the 2009 Robert Wilson Prize and the recognition that comes with it. The citation for the prize reads, 'For his outstanding contribution to the design and construction of accelerators that has led to the realization of major machines for fundamental science on two continents and his promotion of international collaboration.' In this article, he will discuss the two construction projects, which he led, one (TRISTAN e{sup +}e{sup -} Collider at KEK) in Japan and the other (RHIC at BNL) in the USA, covering project issues and lessons learned from these projects. Although both of them were built on separate continents, it is interesting to note that they are both built on long off-shore islands. He will also add comments on his recent engagement in the development of the Conceptual Design for the National Synchrotron Light Source II (NSLS-II).
Date: May 4, 2009
Creator: Ozaki,S.
Partner: UNT Libraries Government Documents Department

SUPER-B LATTICE STUDIES

Description: The SuperB asymmetric e{sup +}e{sup -} collider is designed for 10{sup 36} cm{sup -2} s{sup -1} luminosity and beam energies of 6.7 and 4.18 GeV for e{sup +} and e{sup -} respectively. The High and Low Energy Rings (HER and LER) have one Interaction Point (IP) with 66 mrad crossing angle. The 1258 m rings fit to the INFN-LNF site at Frascati. The ring emittance is minimized for the high luminosity. The Final Focus (FF) chromaticity correction is optimized for maximum transverse acceptance and energy bandwidth. Included Crab Waist sextupoles suppress betatron resonances induced in the collisions with a large Piwinski angle. The LER Spin Rotator sections provide longitudinally polarized electron beam at the IP. The lattice is flexible for tuning the machine parameters and compatible with reusing the PEP-II magnets, RF cavities and other components. Details of the lattice design are presented.
Date: August 25, 2010
Creator: Biagini, M.E.; Raimondi, P.; /Frascati; Piminov, P.; Sinyatkin, S.; /Novosibirsk, IYF et al.
Partner: UNT Libraries Government Documents Department

The Very Large Hadron Collider: The farthest energy frontier

Description: The Very Large Hadron Collider (or Eloisatron) represents what may well be the final step on the energy frontier of accelerator-based high energy physics. While an extremely high luminosity proton collider at 100-200 TeV center of mass energy can probably be built in one step with LHC technology, that machine would cost more than what is presently politically acceptable. This talk summarizes the strategies of collider design including staged deployment, comparison with electron-positron colliders, opportunities for major innovation, and the technical challenges of reducing costs to manageable proportions. It also presents the priorities for relevant R and D for the next few years.
Date: June 21, 2001
Creator: Barletta, William A.
Partner: UNT Libraries Government Documents Department

Measurement of Small Electron Beam Spots

Description: Measurements of transverse beam size are tremendously important to the performance of e{sup +}e{sup {minus}} linear colliders. In this paper we review the traditional technologies used to make such measurements, such as profile monitors and wire scanners, and the limitations on same. We then introduce a new tool for electron beam size measurement: Compton-scattered laser light, which may be used as an unbreakable ''wire'' or in the form of an interferometer beam size monitor. We describe the use of such an interferometer BSM, noting both the general issues related to its design and operation and the specific experiences with such an interferometer at the Final Focus Test Beam (FFTB) at SLAC. We conclude by considering the ultimate limits of the laser-interferometer BSM.
Date: February 3, 1999
Creator: Tenenbaum, Peter G
Partner: UNT Libraries Government Documents Department

A {radical}S = 1 TeV ep collider at Fermilab.

Description: One of the major projects being considered for future construction at Fermilab is a Very Large Hadron Collider (VLHC). This project will require a new High Energy Booster ring, 33 km in circumference, to provide 3 TeV proton beams for injection into the VLHC. Here we discuss the possibility to build an ep collider in the VLHC Booster tunnel. A LEP-like e{sup {+-}} beam (83 GeV) would collide with one of the proton beams (3 TeV) to create a {radical}s {approx} 1 TeV ep collider. Design groups at Argonne and Fermilab have established that it is feasible to build electron injection at the existing infrastructure, and provide a machine with luminosity exceeding 10{sup 32} cm{sup {minus}2} s{sup {minus}1}.
Date: November 16, 1998
Creator: Krakauer, D.
Partner: UNT Libraries Government Documents Department

EXECUTIVE SUMMARY OF THE SNOWMASS 2001 WORKING GROUP : ELECTROWEAK SYMMETRY BREAKING.

Description: In this summary report of the 2001 Snowmass Electroweak Symmetry Breaking Working Group, the main candidates for theories of electroweak symmetry breaking are surveyed, and the criteria for distinguishing among the different approaches are discussed. The potential for observing electroweak symmetry breaking phenomena at the upgraded Tevatron and the LHC is described. We emphasize the importance of a high-luminosity e{sup +}e{sup -} linear collider for precision measurements to clarify the underlying electroweak symmetry breaking dynamics. Finally, we note the possible roles of the {mu}{sup +} {mu}{sup -} collider and VLHC for further elucidating the physics of electroweak symmetry breaking.
Date: June 30, 2001
Creator: CARENA,M.; GERDES,D.W.; HABER,H.E.; TURCOT,A.S. & ZERWAS,P.M.
Partner: UNT Libraries Government Documents Department

Defect profiling in elemental and multilayer systems: Correlations of fitted defect concentrations with positron implantation profiles

Description: The results of several positron annihilation (Doppler broadening) experiments have been analyzed using the BNL Monte Carlo implantation profiles and the program VEPFIT. The program VEPFIT has been modified so that scaled, parameterized multilayer profiles can also be used as the initial condition for the diffusion equation solution. The authors have looked at both elemental (e.g. amorphous silicon) and multilayer (e.g. Pd/Si) system. Strong correlations between the input implantation profile parameters and the fitted values obtained for the diffusion lengths and overlayer thicknesses for the multilayer systems have been found. The effect of uncertainties in the mean depth on the value of the diffusion length and hence the defect concentrations will be discussed. The impact of reimplanting backscattered positrons on both the implantation profiles and the fitted diffusion lengths will also be presented.
Date: August 1, 1994
Creator: Ghosh, V. J.; Nielsen, B.; Lynn, K. G. & Welch, D. O.
Partner: UNT Libraries Government Documents Department

Klystron switching power supplies for the Internation Linear Collider

Description: The International Linear Collider is a majestic High Energy Physics particle accelerator that will give physicists a new cosmic doorway to explore energy regimes beyond the reach of today's accelerators. ILC will complement the Large Hadron Collider (LHC), a proton-proton collider at the European Center for Nuclear Research (CERN) in Geneva, Switzerland, by producing electron-positron collisions at center of mass energy of about 500 GeV. In particular, the subject of this dissertation is the R&D for a solid state Marx Modulator and relative switching power supply for the International Linear Collider Main LINAC Radio Frequency stations.
Date: December 1, 2009
Creator: Fraioli, Andrea & /Cassino U. /INFN, Pisa
Partner: UNT Libraries Government Documents Department

Decays of B_s Mesons and b Baryons: A Review of Recent First Observations and Branching Fractions

Description: Recent rate measurements of B{sub s}{sup 0} mesons and {Lambda}{sub b}{sup 0} baryons produced in {radical}s = 1.96 TeV proton-antiproton and {Upsilon}(5S) electron-positron collisions are reviewed, including the first observations of six new decay modes: B{sub s}{sup 0} {yields} D{sub s}{sup +} K{sup -} (CDF), B{sub s}{sup 0} {yields} D{sub s}{sup -} D{sub s}{sup +} (CDF), B{sub s}{sup 0} {yields} D{sub s1}{sup -}(2536){mu}{sup +} {nu}{sub {mu}} X (DZero), B{sub s}{sup 0} {yields} {phi}{gamma} (Belle)< {Lambda}{sub b}{sup 0} {yields} p{pi}{sup -} (CDF), and {Lambda}{sub b}{sup 0} {yields} pK{sup -} (CDF). Also examined are branching-fraction measurements or limits for the B{sub s}{sup 0} {yields} D{sub s}{sup (*)} D{sub s}{sup (*)} modes (Belle, CDF, and DZero), the B{sub s}{sup 0} {yields} {gamma}{gamma} radiative penguin decay (Belle), and three two-body charmless B{sub s}{sup 0} meson decay channels (CDF). Implications for the phenomenology of electroweak and QCD physics, as well as searches for physics beyond the Standard Model, are identified where applicable.
Date: June 1, 2008
Creator: Warburton, Andreas
Partner: UNT Libraries Government Documents Department

Systematic Improvement of QCD Parton Showers

Description: In this contribution, we will give a brief overview of the progress that has been achieved in the field of combining matrix elements and parton showers. We exemplify this by focusing on the case of electron-positron collisions and by reporting on recent developments as accomplished within the SHERPA event generation framework.
Date: May 17, 2012
Creator: Winter, Jan; Hoeche, Stefan; Hoeth, Hendrik; Krauss, Frank; Schonherr, Marek; Zapp, Korinna et al.
Partner: UNT Libraries Government Documents Department

Exclusive Production of Ds Ds-, Ds* Ds-, and Ds* Ds*- via e e- Annihilation with Initial-State-Radiation

Description: The authors perform a study of exclusive production of D{sub s}{sup +}D{sub s}{sup -}, D*{sub s}{sup +}D{sub s}{sup -}, and D*{sub s}{sup +}D*{sub s}{sup -} final states in initial-state-radiation events from e{sup +}e{sup -} annihilations at a center-of-mass energy near 10.58 GeV, to search for charmonium 1{sup --} states. The data sample corresponds to an integrated luminosity of 525 fb{sup -1} and was recorded by the BABAR experiment at the PEP-II storage ring. The D{sub s}{sup +} D{sub s}{sup -}, D*{sub s}{sup +}D{sub s}{sup -}, and D*{sub s}{sup +}D*{sub s}{sup -} mass spectra show evidence of the known {psi} resonances. Limits are extracted for the branching ratios of the decays X(4260) {yields} D{sub s}{sup (*)+}D{sub s}{sup (*)-}.
Date: October 27, 2010
Creator: del Amo Sanchez, P.; Lees, J.P.; Poireau, V.; Prencipe, E.; Tisserand, V.; /Annecy, LAPP et al.
Partner: UNT Libraries Government Documents Department

Measurement of the Absolute Branching Fractions for $D^-_s\!\rightarrow\!\ell^-\bar{\nu}_{\ell}$ and Extraction of the Decay Constant $f_{D_s}$

Description: The absolute branching fractions for the decays D{sub s}{sup -} {yields} {ell}{sup -}{bar {nu}}{sub {ell}} ({ell} = e, {mu}, or {tau}) are measured using a data sample corresponding to an integrated luminosity of 521 fb{sup -1} collected at center of mass energies near 10.58 GeV with the BABAR detector at the PEP-II e{sup +}e{sup -} collider at SLAC. The number of D{sub s}{sup -} mesons is determined by reconstructing the recoiling system DKX{gamma} in events of the type e{sup +}e{sup -}DKXD*{sub s}{sup -}, where D*{sub s}{sup -} {yields} D{sub s}{sup -}{gamma} and X represents additional pions from fragmentation. The D{sub s}{sup -} {yields} {ell}{sup 0}{nu}{sub {ell}} events are detected by full or partial reconstruction of the recoiling system DKX{gamma}{ell}. The branching fraction measurements are combined to determine the D{sub s}{sup -} decay constant f{sub D{sub s}} = (258.6 {+-} 6.4 {+-} 7.5) MeV, where the first uncertainty is statistical and the second is systematic.
Date: October 27, 2010
Creator: del Amo Sanchez, P.; Lees, J.P.; Poireau, V.; Prencipe, E.; Tisserand, V.; /Annecy, LAPP et al.
Partner: UNT Libraries Government Documents Department

Rare And Radiative B Meson Decays From the BaBar Experiment

Description: Since its start in 1999 the BABAR experiment has collected a vast amount of data. Electron-positron collisions at the energy of the {Upsilon}(4S) resonance have produced about 240 million coherent B{sup 0}{bar B}{sup 0} and B{sup +}B{sup -} pairs, opening the doors for exploration of rare B meson decays. An overview of the electroweak penguin physics program of BABAR is given, the analysis of two specific decays is presented in detail.
Date: August 28, 2006
Creator: Stelzer, J.
Partner: UNT Libraries Government Documents Department

Beam Instrumentation Challenges at the International Linear Collider

Description: The International Linear Collider (ILC) is a proposed facility for the study of high energy physics through electron-positron collisions at center-of-mass energies up to 500 GeV and luminosities up to 2 x 10{sup 34} cm{sup -2} sec{sup -1}. Meeting the ILC's goals will require an extremely sophisticated suite of beam instruments for the preservation of beam emittance, the diagnosis of optical errors and mismatches, the determination of beam properties required for particle physics purposes, and machine protection. The instrumentation foreseen for the ILC is qualitatively similar to equipment in use at other accelerator facilities in the world, but in many cases the precision, accuracy, stability, or dynamic range required by the ILC exceed what is typically available in today's accelerators. In this paper we survey the beam instrumentation requirements of the ILC and describe the system components which are expected to meet those requirements.
Date: May 16, 2006
Creator: Tenenbaum, Peter
Partner: UNT Libraries Government Documents Department